Apparatus for use on floating drilling platforms



Sept. 28, 1965 M. H. PARKS APPARATUS Fon usf: on momma Immune PLATFORMS A Filed Nov. 19, 1962 3 Sheets-Sheet 1 y vFIGL.

` APPARATUS" FOR USE 0N -FLOATING DRILLING PLATFORMS y Filed Nov. 19,' 1962 M. H. PARKS Sept. 28, 1965 I 3 sheets-sheet 2 l I I l l l I l l I I l l l l I .l I To mm m m. u. n o w." M n .a m) P M m .K 0 2. ,w. M M ,.9 W I 71H .r

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Sept. 28,1965 M. H. PARKS 3,208,728

APPARATUS Fon USE oN FLOATING DRILLING PLATFORMS Filed Nov. 19.*,l 1962-. I

3 Sheets--Shaet 3 ATTORNEY;

United States Patent lig,

3,208,728 APPARATUS FOR USE N FLOAT'ING DRILLENG PLATFQRMS Mercer H. Parks, Houston, Tex., assignor, by meme assignments, to Esso Production Research Company, Houston, Tex., a corporation of Delaware Filed Nov. 19, 1962, Ser. No. 238,397 Claims. (Cl. 2541-172) The present invention` concerns apparatus for maintaining a substantially constant tension on drill pipe and the like suspended from a oating offshore structure.

When drilling wells into submerged lands from floating offshore drilling platfonns,"substantially constant weight must be maintained on the drill bit to keep it from beingV alternately pulled away from and dashed against lthe bottom of the borehole as wave action causes the floating platforms to vertically oscillate. Also, when running logging apparatus intoor pulling it from a submerged bore,-

oscillations of the floating platform will not prevent uniform travel of the logging equipment. A stable suspensionA point also is required to maintain completion equipment such as gun perforators at a desired level in the borehole when completing wells from oating offshore platforms. n, l

It is a primary purpose of the present invention to provide apparatus to meet these needs.

One embodiment of the invention includes acylinder and piston 'from which is suspended `-well drilling equipment and means including accumulators mounted on the cylinder forsupplying constant pressure, variable volume hydraulic energy to the cylinder.

Another embodiment of the invention includes a piston and cylinder connected 'to a fixed point throughresilient g means; a reel for supporting a cable from which well .equipment is suspended arranged on said resilent means connection; and means for supplying constant pressure, variable volume hydraulic energy tothe .clylinden The `above object and other objects and advantages of the invention will be apparent from a more detailed description thereof when taken with the drawings wherein:

" FIG. 1 is a vertical view of a drilling platformoating 'on 'a body of water with the apparatus ofthe invention y the invention for use in conjunction with logging appa- *.ratus; and

FIG. 7 is a view similar to that shown in' FIG. 6 but illustrating a different embodiment. Referring to the drawings in greater detail, in FIG. 1 is shown an offshore drilling platform or barge 10 anchored and floating in arbody of water 11, and on which is'arranged conventional drilling equipment, including derrick structure 12, live line 13, dead line 14,crown bloclc 15, traveling block 16, circulating uid conduit 18, swivel 19, rotary 20, and draw works 21. A borehole is being drilled in the area underlying the body of water 11 by means of a drill bit 26 carried on the end of a string of drill pipe 27, the upper end of which is connected to a Kelly joint 28, which in turn is connected to the swivel v1'9. `A part of the apparatus for maintaining substantially constan-t weight on drill bit 26 to compensate for vertical movement of platform 10 generally designated 30a is in- -2 hole, a stable suspension point must be established so that terposedbetween block 16 and swivel 19. The remainder of the compensating apparatus generally-designated 30b is positioned on the drilling platform.

Details of apparatus 30a and 30b are shown in FIGS. 2-5. Part 30a of this apparatus includes an elongated cylinder suspended from traveling block 16 by links 36. Cylinderl 35 is provided with an opening 37 in its upper end and an opening 38 in its lower end. The latter opening has connected to it a conduit 39. A piston 40, which divides the interior of cylinder 35 into upper and lower chambers 41 and 42 respectively,is slidably arranged in cylinder 35. A rod 43, from which drill pipe string 27 and drill bit 26 arev suspendedthrough swivel 19,-'extends through the lower end of cylinder' 35 and is attached to piston 40. A seal 44, arranged in the lower end of cylinder 35, closes olf the space surrounding rod 43 in the opening in cylinder 35 through which rod 43'extends in order to prevent leakage of liquids from chamber 42. Three accumulators 45 are secured to cylinder 35 by means of ,upper and lower brackets 46. Each accumulator is provided with `a floating or free piston 47 which di'- vides the 'interior of each accumulator into upper gascontaining and lower liquid, e.g., oil or water-containing chambers 48 and 49 respectively. High pressure gas is through a conduit 68 and feeds it to conduit 39.

supplied to chamber 48 through nipple 510,a manifold 51 and a conduit 52. Valves 53 and 54 and a pressure regulator 55 are in conduit 52` which connects'to a static source of uid pressure`56 (see FIG. 5) as for example, nitrogen bottles. Lower chambers 49 uidly communicate with a reservoir of liquid 60 through a connecting manifold 61 and a conduit 62.' Conduit 39 also connects into manifold 61. A conventional, commercially available, diaphragm-operated motor valve 63, suchfas disclosed on -page 1864, Composite Catalog of Oil Field Equipment and Services, 1962-63, is arranged in conduit 62 and controls liow of liquid therethrough. Valve V63 is in turn controlled by liquid pressure in conduit 39, through a connecting conduit 64. A manually operable valve 65 is positioned in conduit 39. The remainder of apparatus 30b, as seen inl FIG. 5, includes a pump 66 which-`when driven byv a motor 67 draws liquid from reservoir 60 The pressure of theoil in chamber 42 determines the force or weight on drill bit 26..., The higher thepressure in chamber 42, the less will be the weight on the drill bit;

and accordingly, the`lesser the pressure in chamber 42,`

by vertical movement of cylinder 35, resulting from vertical movement of platform 10, must be compensated for by the pressure system described supra. Accumulators 49 provide a rapid Iresponse to pressure transients caused by the vertical motion of drilling platform 10, whereas reservoir 60 and its associated equipment, pump 66 and motor valve 63, provide for system,` volume changes associated with increased depth of borehole 25 as drilling progresses, and large movements of drilling platform 10.

The apparatus of FIGS 1-5 operates in the following manner. When wave action causes drilling platform 10 to rise cylinder 35 also is carried upwardly relative to piston 40; and downward movement of platform 10 causes cylinder 35 to move downwardly relative to piston 40. When cylinder 35 rises relative to piston 40, pressure of the oil in chamber 42 increases.

Patented sept. 2s, 1965A To maintain t the.` accumulators arey ,l 3 pistonv 40 at al relatively constant level, liquid in chamber 42 discharges through conduit 39 andv manifold 61 into chambers 49 of accumulators 45 where the increased pressure acts against: lioatingk pistons 47 to move-them upwardly and yincrease in turn the pressure of the vgas in chambers.48,.` Excess pressure in chambers 48l may be released throughl a pop-off valve 51a arranged in` manifold '1'. Onr the other hand, when cylinder 35" moves downwardlyjn'response to vdownward .movement of platform y10, in order to maintain piston 40 at' a constant level, liquidmust be supplied to chamber42 to compensate for the decreased pressure caused by the increased 1 volume ofl chamber 42'. 'This liquid is. supplied by that in chambers 49. and is forced through'conduit 39 via a manifold 61ninto chamber 42 by gas pressure in chambers 48 suppliedr thereto fromy the gasstorage 56.

Pump y66iis .operated continuously to.force yliquid from reservoirf 60 into chamber 42 through conduit 39. Once the pressure'in `chamber 42 has been equalized by the liquid supplied fromcha'mbcrs 49 of accumulators 45,.

additional'liquid'from reservoir 60is lsupplied to chambers 49, as required to effect' full compensation for movementof plat-form Also, when excess liquid 4 and drill bit. Thus, a traveling-block 16 connects to a cylinder' through links 36', and accumulator cylinders 45 are mounted on cylinder 35', Theupper ends of cylinder 45 tiuidly communicate with'a' source of fluid pressure through conduit 50 and 51 :and manifold 52.

, A rod 70, .Which Connects to the piston in'fcylinder 35', is

coupled to a turnbuckle 71*v by a tension springv 72. The lower end of tumbuckle 7.1' is secured to the wellhead 73 at a fixed point '74, which may be eitherbelow water surface as shown"y or-above' it. .A sheave 75'is clamped as at 76 to rod 70'. A logging cable77 feeds from a from chamber'42'wattempts to feedinto chambers 4 9, `asl l moves downward, it is discharged into reservoir 60 through valve63` by the pressure controlled conduit 64,

' which senses the increased .liquid-pressure inv conduit '39.v

The excess .liquid pressure Vthen is discharged into .reservoir 60. In general, small movements of cylinder 35 resulting rom Slight waveactionwill be compensated for by liquid transmitted from and intoaccumulators 45, whereas large 'movements of" cylinderI 35i will be offset 'by pump 66 and reservoir 60,' as well as accumulators 45` and staticrsource56 The pressures in the system must'be increasedto compensate for the additional l'wei'ght of the vdrill stringwhen lengths of drill pipe areV added as the borehole is drilled deeper' and deeper, orl increased or. decreased whenv it is desiredto increase or: decrease'respectively, the weight it' is desired-to maintain on the drill bit; Dimensions vand working'pressuresaren-dependentupon .the'variousphysieal factors" which. will be well known for specific applications and. upon engineering judgment in such matters a materials and safetyfactors.

The sensitivityof'. control of the position of piston 40 depends onv the compressibility andvolume-of gas contained in accumulators 45. As` mentioned supra, to maintain sensitivity of accumulators 45 as the operating pressurelevel increases, itis necessary to add gas to Achambers 48 as the ldepth of the'drill hole increases, and

4to supply' gasto vchambers .48,- anairreceivercontinuously charged by anair'compressor may be employed instead 1 of 'the vgas bottles '56shown.

Accumulators tare mounted adjacent control :cylinder 35 in order4 to eliminate any time lag in response to movement'of cylinder 35.` As an example, assume drilling platform 10'is oating in l5.foot waves, withv a possiblityv of having a vertical velocity. of 1'0 to 20 feet perA spool lor reel 78'mounted on drilling platform 10 through a pulley 79 also vmountedon drilling platforml0 and over reel 75.

In the FIG. 6 embodiment the apparatus for supplying uid pressure tothe underside ofthe piston in cylinder 35 to maintain aconstant weight on the logging tool, or to lmaintain the completion tool in'a s teadyrposition in the borehole, is the `same as that3 described forthe drilling apparatus of FIGS. 1-5. v

However, in'FIG. 7 a somewhat different'arrangement is shown .in which the motor valve is controlled by a solen'oidratherl than iluid pressure. Thus, valve 80 is controlled through line v81 by a Whea-tstone bridge 82 mounted on one of the accumulators 45'. In turn, the Wheatstonebridge 82 is'controlled by a line 83 vconnected toa `strain gauge 84, mounted on rod 70 vbelow -reel 75.

The operation of this equipment is as follows: In thel apparatus of FIG. 6 movement of drilling platform 10 upwardly or downwardly increases or decreases the tension vin rod 70, `whichhasy been preset by adjusting turnbuckle 71'and spring 72. The change in tension in rod 70 produces achange in the pressure in cylinder 35',below the` piston, which'is reflected through the conduit Ato open pressure operated valve 63 .to restore the liquid 'pressureiniti'ally existing'and'through .it the tensioninitially existing in rod '70, and the vertical position lof reel 75. The operation ofthe apparatus of FIG. 7 is similar, except that in this instance a strain gaugev 84' transmits increases or decreases-in the tension in rod 70 to Wheatstone bridge 82,'

of `fluid' from cylinder 35'.. As in the case'of'the apparatus formaintaining'bit weight, dimensions and working. pressuresl will depend vupon known physical factors andengi- `neering .judgment for each application.

Having fullyfdescribed the nature, objects, and elements of my invention, I claim:

1. Apparatus for suspending a tool-ina. borehole on a cable from-a oating offshore drilling platformy comprissecond. Totcompensate the piston for this movement of cylinder' 35;,.the controls must respond rapidly enough to preventappreciable movement of the position ofswivel 19; When lthe hydraulic uid is transmittedthrough a greatlength ofipipingthe time for the pressure impulses to travel throughvthis liquid may permit movement yof the yswively some distance which, of course,`is not desired.

Therefore, Vin order to make the apparatus more sensitive, mounted adjacent the control cylinder. `Arrangements ofA apparatusffor running logging and .completion tools from oating olshoretstructures in submerged 'wells are shown in FIGS. 6-and"7'. The compensating apparatus is similar to that described for the Y to'V support equipment much lighter than the drill string means':mounted on said platform attached to said cableV for raising 'and lowering it;`

suspension means mounted, oul said platform including 7 a cylinder having a piston slidably arranged therein; liquid in said cylinder below said piston;` f tension means yhaving an adjustabletension preset to a selected tension securing said movable point;

a sheave attached to saidtension means" over which said cable .is'fed; and

- means responsive to changesin ltension-in said tension means resulting from vertical movementof said platform adapted to compensate f or motion'ofv the tool arising from displacement of the platform and suspension means. ,5

2. Apparatus as recited inclaim' 1 in which said tension means includes means for releasing more orzfless liquid from said cylinder in response to increases or decreases in means comprises a rod, a spring and a tumbuckle connected together.

4. Apparatus as recited in claim 3 infwhich said means responsive to changes in tension nsaid tension means comprises a strain gauge attached to said rod; a Wheatstone bridge controlled by said strain gauge; and a solenoid valvecontrolled by said Wheatstone bridge.

5. Apparatus as recited in claim 4 including at least one accumulator mounted on said cylinder having a movable pressure responsive member dividing said accumulator into rst and second chambers; means for supplying gas 3 under pressure to said accumulator first chamber, said ac- 1 cumulator second chamber containing liquid in fluid com- 5 LOUIS J. DEMBo, Primary Examiner.

f 6 munication with said cylinder; a liquidv reservoir; and'a pump for supplying said cylinder with liquid, said reservoir liquid being `in uid communication v ia said pump with said accumulator second chamber.

i References Cited by the Examiner UNITED STATES PATENTS 2,109,297 2/ 3 8 McMurry.

2,732,180 1/ 56 Gratzmuller 2551-7172 10 2,857,138 10/58 Svendsen 175-27 2,945,676 L, 7/60 Kammerer 175-5 3,15 8,206 1 1/ 64 Kammerer l -175-5 3,158,208 11/64 Kammerer 175-5 L SAMUEL F. COLEMAN, Examiner. 

1. APPARATUS FOR SUSPENDING A TOOL IN A BOREHOLE ON A CABLE FROM A FLOATING OFFSHORE DRILLING PLATFORM COMPRISING: MEANS MOUNTED ON SAID PLATFORM ATTACHED TO SAID CABLE FOR RAISING AND LOWERING IT; SUSPENSION MEANS MOUNTED ON SAID PLATFORM INCLUDING A CYLINDER HAVING A PISTON SLIDABLY ARRANGED THEREIN; LIQUID IN SAID CYLINDER BELOW SAID PISTON; TENSION MEANS HAVING AN ADJUSTABLE TENSION PRESET TO A SELECTED TENSION SECURING SAID PISTON TO A FIXED, IMMOVABLE POINT; A SHEAVE ATTACHED TO SAID TENSION MEANS OVER WHICH SAID CABLE IS FED; AND MEANS RESPONSIVE TO CHANGES IN TENSION IN SAID TENSION MEANS RESULTING FROM VERTICAL MOVEMENT OF SAID PLATFORM ADAPTED TO COMPENSATE FOR MOTION OF THE TOOL ARISING FROM DISPLACEMENT OF THE PLATFORM AND SUSPENSION MEANS. 